The Children's Hospital of Philadelphia (CHOP) is a primary treatment center for children with malignant diseases. As a member institution of Children's Cancer Study Group A (CCSG) the study and treatment of these diseases will be pursued via the protocols of CCSG. Chemotherapy will be used alone or in conjunction with surgery and/or radiation therapy, according to the dictates of the protocols, to try to determine less toxic and more effective means of improving survival in children with leukemia and solid tumors. Members of the Surgical, Pathology and Radiation Therapy Divisions will actively participate in developing and conducting these studies. Collaboration with other Cooperative Groups will be achieved through the mechanism of Intergroup Studies. The aims of CCSGA may be succinctly stated as follows: 1. To determine the most effective treatment methods for children with malignant diseases. 2. To design and test new concepts of treatment and new agents. 3. To involve surgeons, radiotherapists and pathologists early in the design of cancer studies in order that: a) results of the total treatment can be analyzed b) more can be learned about the natural history of the diseases, including histopathology and epidemiology. 4. To widely disseminate the findings of the various studies. BIBLIOGRAPHIC REFERENCES: Hittle, R., Weiner, J., Ortega, J., Donaldson, M., Karon, M., and Nesbit, M.: Effectiveness of presymptomatic treatment (pretherapy) on the occurrence of central nervous system (CNS) disease in childhood lymphoblastic leukemia (ALL). Proc. American Association for Cancer Research and the American Society of Clinical Oncology, Inc., San Diego, California, May 7, 1975. Vol. 16, Abst. #1143, p. 256. Bound with Cancer Research, Vol. 35; Ortega, J., Nesbit, M., Donaldson, M., Weiner, J., Hittle, R., and Karon, M.: L-asparaginase, vincristine and prednisone in acute lymphocytic leukemia (ALL). Proc. American Association for Cancer Research and the American Society of Clinical Oncology, Inc., San Diego, California, May 7, 1975. Vol. 16, Abst. #588, p. 140. Bound with Cancer Research, Vol. 35.